From a nominal point of view, all were world champions, all were undefeated, then we look at the numbers: 54| Wanheng Menayothin 50| Floyd Mayweather 49| Rocky Marciano If Floyd Mayweather can dirty Wanheng Menayothin perfect record, with a draw, then Wanheng Menayothin falls into the Ricardo Lopez imperfect category and Floyd becomes #1 again.